How to diagnose, repair, and info on symptoms and causes of a P2604 engine code which applies to diesel vehicles with an air intake heater. This is a circuit problem that relates to range or performance. Also includes links to relevant forum discussions on the code.

Symptoms of P2604 OBD II Trouble Code

Engine will not start

Longer than normal cranking time

Check Engine Light illuminated

Rough idle at cold temperatures

Engine stalls

Common Causes of P2604 OBD II Trouble Code

Faulty heater element relay

Detective heater element

Faulty temperature sensor

Corroded or damaged connector

Damaged or restricted air duct

Faulty or damaged wiring

Defective Blower motor

Faulty PCM

Severity of P2604 OBD II Trouble Code

The severity of this code is normally moderate, but can be severe based on the specific malfunction.